This invention pertains to fenders for vessels, that is, devices of the type used in connection with mooring a floating vessel to a wharf, wherein the device is capable of dissipating energy or otherwise responding so as to protect vessel and wharf from damage caused by motion of one relative to the other.
A vessel, and especially a pleasure boat, is apt to be moored at a wharf unattended for days and weeks at a time. Pleasure boats commonly range in a length from 15 feet (4.6 m) to 50 feet (15.2 m), but there are a considerable number of pleasure boats having lengths outside this range. If the wharf is located on a narrow fairway subject to the action of the winds, the hull of a boat so moored, as well as the wharf to which it is moored, is subject to damage from the continual pitching and rolling of the boat and from its bumping and rubbing against the wharf caused by the wakes of passing boats and the natural winds and waves.
A conventional method of protection from such damage to hull and finish, especially for smaller boats, is the use of cushioning bumpers of various sorts, such as braided rope or, more commonly, pneumatic bumpers, available in various shapes, hung between boat and wharf. For ships and other large vessels there are other cushioning devices which can be attached at points along a wharf.
Another method of protection is to line the edge of the wharf with cushioning material such as old fire hose, or with rubber or plastic lineal extrusions made for the purpose.
Another protective method is to tie the boat away from the wharf to an opposite wharf or piling set away from the wharf.
Another protective method employs flexible glass fiber poles or whips, the butt ends of which are held in special holders on the wharf and the tip ends of which are bent and tied to the boat with ropes in such a way as to fend it away from the wharf.
All of the above approaches leave much to be desired for a variety of reasons. Some of these reasons are discussed below.
Bumpers hung from the boat or wharf do not operate over a wide enough gap between boat and wharf. They only exert a fending force when they are actually being compressed between the boat and the wharf and, because the distance over which the bumper can be compressed is comparatively small (a very few inches at best), the fending forces exerted on the hull and wharf are comparatively very large and damaging to the hull. Further, when boat-mounted bumpers are not under compression, they continually swing back and forth against the hull, from the pitching and rolling of the boat, and eventually this action chafes and mars the hull. Ship bumpers installed at points along a wharf also exert concentrated large forces which might be harmful.
Linear cushioning means lining the edge of the wharf also exert strong forces against the hull and eventually chafe and mar it.
The opportunity for tying off to other wharfs or pilings is not always available, and, when it is, the process of tying off is an awkward maneuver to accomplish.
Whips made of glass fiber are expensive, ineffective against strong forces, and non-stowable aboard.
There is disclosed in U.S. Pat. No. 2,842,939, issued for an invention of P. A. D'Auriac, a shock absorber for docking of ships. This shock absorber in its preferred embodiment comprises a pair of shoes for contacting the hull of a ship and a rather complex carriage structure for supporting the shoes resiliently away from the dock side. The carriage moves on a vertical track on the dock side. The shock absorber therefore cannot be used unless the dock has available a side on which the carriage may be mounted. In many instances, such a side may not be available, or if available, the use thereof may be inconvenient. Furthermore, the carriage structure may be undesirably expensive and cumbersome, particularly in connection with the mooring of pleasure boats.